Because of the energy gap law, as well as the spin-forbidden nature of triplet formation and transformation, it remains formidable task to achieve efficient and long-lived organic afterglow materials with long emission wavelengths, especially in the near-infrared region, under ambient conditions. Here we incorporate TADF-type afterglow mechanism in dopant-matrix systems which features a moderate k(RISC) of 10(1)-10(2) s(-1) to harvest triplet energies, boost afterglow efficiency and maintain afterglow lifetime. Specifically, we design a series of boron difluoride curcuminoid (CurBF(2)) compounds to serve as luminescent dopants. Organic matrices of crystalline nature and with carbonyl groups are selected to suppress triplet quenching by their rigid microenvironment and populate triplet states via dipole effect developed in our group. The resultant dopant-matrix systems display near-infrared TADF-type organic afterglow with emission wavelength >700 nm, quantum yield around 10 % and afterglow lifetime >10 ms, which can function as deep-penetrating and background-independent bioimaging probes.

A series of polymeric chiral diamine ligands are developed by diboron-templated asymmetric reductive couplings, and their iridium complexes Ir-polydiamines are efficient and recyclable catalysts for asymmetric transfer hydrogenation (ATH) of functionalized ketones, affording a series of optically active secondary alcohols in excellent enantioselectivities (up to 99% ee) and unprecedentedly high total TONs (12,000, six cycles). Ir-polydiamine catalysts with longer chains offered higher reactivities, providing a plausible deactivation mechanism and practical solutions of ATH for vitamin B5 and phenylephrine.

Fusicoccane diterpenoids, originating from fungi, plants, and bacteria, constitute a diverse natural product family featuring a 5-8-5 tricyclic framework. They were restricted to plant physiology in the past. However, fusicoccanes are presently at the forefront of biomedicine and are indispensable for probing 14-3-3 protein-protein interactions (PPIs). The need for material supply and scaffold diversification encouraged their study by the synthetic community. This review highlights the total synthetic works on fusicoccane diterpenoids published in the last 5 years. Key transformations including ring-closing metathesis, metal-catalyzed cross-coupling, and carbocyclization markedly enhanced synthetic efficiency and versatility. Recently identified biosynthetic transformations inspired innovative chemoenzymatic strategies. Investigation into the functional aspects of fusicoccanes should be the future direction to realize their therapeutic potential as general 14-3-3 PPI modulators.

The first successful copper-catalyzed decarboxylative cyclization reaction of ethynylbenzoxazinones and thiols has been developed. A rarely studied alpha-addition process to a copper-allenylidene intermediate promoted this reaction. Using this protocol, a range of 2-thiomethylene indole compounds have been obtained. This methodology offers significant advantages including mild reaction conditions, cheap catalysts, good yields and broad substrate compatibility. The first successful copper-catalyzed decarboxylative cyclization reaction of ethynylbenzoxazinones and thiols has been developed, involving a rarely studied alpha-addition process to a copper-allenylidene intermediate.

The nucleophilic trifluoromethylation involving trifluoromethyllithium (LiCF3) species has been an open question since Haszeldine attempted to prepare LiCF3 in 1949. Indeed, LiCF3 has been used for electrophilic difluoromethylene transfer processes (via elimination of fluoride ions) since 2010. Herein, we demonstrated that by using a polar solvent such as dimethylformamide (DMF) or hexamethylphosphoramide (HMPA) as the lithium chelator, the in situ deprotonation of fluoroform (HCF3) with lithium hexamethyldisilazide (LiHMDS) could generate a tamed LiCF3 species that is sufficiently persistent to undergo nucleophilic trifluoromethylation reaction. The nucleophilic reactivity of LiCF3 species was probed with several electrophiles, including arylsulfonyl fluorides, diaryl ketones, and silyl chlorides. The synthetic utility of this method is demonstrated with the efficient synthesis of highly valuable triflones that are otherwise difficult to synthesize from HCF3 using potassium or sodium bases. This work not only showcases a new protocol for the utilization of fluoroform (an industrial waste with high global warming potential) as the trifluoromethylation reagent, but also provides intriguing insights into the harnessing of nucleophilic reactivity of the transient LiCF3 species.

A diarylurea-containing phosphine ligand-modulated stereoinvertive O-glycosylation with primal furanosyl and pyranosyl ortho-alkynylbenzoate (ABz) donors under gold(I) catalysis is disclosed. Both alpha- and beta-configured glycosides could be obtained from the corresponding stereochemically pure beta- and alpha-glycosyl donors with high yields and good to excellent stereoselectivities, respectively. This method accommodates a variety of glycosyl donors and alcoholic acceptors, leading to both 1,2-cis and 1,2-trans glycosidic linkages, and has been applied to the convenient preparation of a series of linear arabinan glycans. Mechanistic investigations reveal that the counteranion could bridge the diarylurea residue on the phosphine ligand with the alcoholic acceptor via hydrogen bond interactions, thereby permitting stereoinvertive displacement at the anomeric position.

Closo-Hexaborate (closo-B6H62-) can engage in nucleophilic substitution reactions with a wide variety of alkyl electrophiles. The resulting functionalized boron clusters undergo oxidative electrochemical deconstruction, selectively cleaving B-B bonds while preserving B-C bonds in these species. This approach allows the conversion of multinuclear boron clusters into single boron site organoboranes. Trapped boron-based fragments were isolated from the electrochemical cluster deconstruction process, providing further mechanistic insights into the developed reaction. In situ generated hexaborate dianions can engage in nucleophilic substitution followed by bulk electrolysis to produce organoboronate esters.

Matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) has shown its capability in visualizing the spatial distribution of various kinds of endogenous metabolites. Nevertheless, high quality mass imaging of low polar metabolites remains challenging. Herein, a platform for sensitive matrix-assisted laser desorption ionization-mass spectrometry imaging of cholesterol and glycerides has been proposed. In the platform, a vacuum promoted on-tissue derivatization strategy was proposed to constantly make the derivatization reaction proceed towards to the direction of products. Compared with traditional on-tissue derivatization procedure, the strategy improved the acquired intensity of derivatized glycerides about 50 %. Additionally, the mass spectrometry image reflecting the signal ratio between 3 classes of glycerides was achieved to exploit the metabolic level of glycerides on tissue slice. Finally, the platform was applied to brain slices of Alzheimer's transgenic mice, type 2 diabetes mice and normal mice. Significant difference was found in mass spectrometry images reflecting the signal ratio of multiple endogenous metabolites. The work constructed a promising platform for mapping of glycerides in tissue by mass spectrometry imaging. (c) 2024 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.

Owing to substantial advances in the past several decades, transition-metal-catalyzed asymmetric reactions have garnered considerable attention as pivotal methods for constructing chiral molecules from abundant, readily available achiral counterparts. These advances are largely attributed to the development of chiral ligands that control stereochemistry through steric repulsion and other noncovalent interactions between the ligands and functional groups or prochiral centers on the substrates. However, stereocontrol weakens dramatically with increasing distance between the reaction site and the functional group or prochiral center. Herein, we report a symphonic strategy for remote stereocontrol of Rh(III)-catalyzed asymmetric benzylic C-H bond addition reactions of diarylmethanes in which the two aryl motifs differ at the meta and/or para position. Specifically, catalysts bearing a new type of chiral cyclopentadienyl (Cp) ligand differentiate between the two aromatic rings of the diarylmethane by arene-selective eta(6) coordination, setting up an opportunity for ligand-controlled stereoselective benzylic deprotonation and subsequent stereoselective addition to the 1,1-bis(arylsulfonyl)ethylene.

We report a novel strategy for the synthesis of chiral 2-oxazolidinones via a dinuclear copper-catalyzed asymmetric propargylic amination-carboxylative cyclization sequence of propargylic esters with nucleophilic alkyl amines under ambient pressure of carbon dioxide. A variety of chiral 2-oxazolidinones featuring an exocyclic methylene moiety was obtained in good yields with high enantioselectivities via a one-pot operation. A variety of chiral 2-oxazolidinones was obtained via a dinuclear copper-catalyzed asymmetric propargylic amination-carboxylative cyclization sequence of propargylic esters with alkyl amine hydrochlorides and CO2.

Here, we report the preparation of lactones via Ni-catalyzed alkene hydroxylarylation and sequential intramolecular lactonization with O-2 as a green oxidant and oxygen source. The bulky 1,3-diketone ligand is crucial by enabling Ni-catalyzed hydroxylarylation of alkenes, providing numerous phthalide and furanone derivatives with high efficiency under mild conditions. The synthetic value of this methodology was further demonstrated by the efficient synthesis of typhaphthalide and a monoamine oxidase B inhibitor.

Cold-adapted species are able to generate cryoprotective proteins and glycoproteins to prevent freezing damage. The [-> 4)-beta-D-Manp-(1 -> 4)-beta-D-Xylp-(1 ->]n xylomannan from the Alaska beetle Upis ceramboides was disclosed by Walters and co-workers in 2009 as the first glycan-based antifreeze agent, which was later reported to be found in diverse taxa. Here, we report the rapid synthesis of four types of xylomannans, including the proposed antifreeze xylomannan up to a 64-mer (Type I), the regioisomeric [-> 3)-beta-D-Manp-(1 -> 4)-beta-D-Xylp-(1 ->]n 16-mer (Type II), the diastereomeric [-> 4)-beta-L-Manp-(1 -> 4)-beta-D-Xylp-(1 ->]n 16-mer (Type III) and the block-wise [-> 4)-beta-D-Manp-(1 ->]m[-> 4)-beta-D-Xylp-(1 ->]n 32-mer (Type IV), by employing a strategic iterative exponential glycan growth (IEGG) process. The nuclear magnetic resonance spectral data of the alleged natural xylomannan are in accordance only to those of the block-wise Type IV glycan and none of these synthetic xylomannans has been found to be capable of inducing thermal hysteresis. These results disprove the previous reports about the natural occurrence of antifreeze xylomannans. The alleged natural antifreeze xylomannan has been disproved via the chemical synthesis of four types of xylomannan glycans using the gold(I)-catalyzed strategic iterative exponential glycan growth (IEGG) process.